As one of new types of high-power and high-energy density rechargeable batteries, a rechargeable lithium battery has been recently utilized which is charged and discharged by the transfer of lithium ions through a nonaqueous electrolyte solution between the positive and negative electrodes.
For such a rechargeable lithium battery, a negative electrode using a lithium-alloying material, such as silicon, for the negative active material has been studied. However, in the case where the lithium-alloying material, such as silicon, is used as the active material of the negative electrode, the active material is powdered or falls off from the current collector during charge and discharge because the active material expands and shrinks in volume when it stores and releases lithium. This lowers the current-collecting capacity of the electrode and accordingly deteriorates charge-discharge cycle performance characteristics, which has been a problem.
The present applicant has proposed an electrode which uses silicon as active material and improves cycle performance characteristics of rechargeable lithium batteries (Patent Document 1). More specifically, the electrode has a noncrystalline silicon thin film deposited on a current collector by a thin film-forming method such as a sputtering, chemical vapor deposition (CVD process) or evaporation method. The present applicant has also proposed an electrode, for use in rechargeable lithium batteries, fabricated by incorporating cobalt or other element into silicon (Patent Document 2). For rechargeable lithium batteries using carbon material or metallic lithium as a negative active material, dissolving of carbon dioxide in nonaqueous electrolytes has been proposed (for example, Patent Documents 3-13).    Patent Document 1: PCT Int. Publication No. WO 01/29,913    Patent Document 2: PCT Int. Publication No. WO 02/071,512    Patent Document 3: U.S. Pat. No. 4,853,304    Patent Document 4: Japanese Patent Laid-Open No. Hei 6-150975    Patent Document 5: Japanese Patent Laid-Open No. Hei 6-124700    Patent Document 6: Japanese Patent Laid-Open No. Hei 7-176323    Patent Document 7: Japanese Patent Laid-Open No. Hei 7-249431    Patent Document 8: Japanese Patent Laid-Open No. Hei 8-64246    Patent Document 9: Japanese Patent Laid-Open No. Hei 9-63649    Patent Document 10: Japanese Patent Laid-Open No. Hei 10-40958    Patent Document 11: Japanese Patent Laid-Open No. 2001-307771    Patent Document 12: Japanese Patent Laid-Open No. 2002-329502    Patent Document 13: Japanese Patent Laid-Open No. 2003-86243